2013/09/20 by Tri Lai, Lai, Tri
Mathematics · #05A15 #05E99 #Combinatorics (math.CO) #FOS: Mathematics #math.CO #msc:05A15 #msc:05E99
paper · pdf · doi:10.48550/arxiv.1309.5376
35 pages, 31 figures
arxiv created 2013/09/20 · arxiv updated 2013/09/24
We solve and generalize an open problem posted by James Propp (Problem 16 in New Perspectives in Geometric Combinatorics, Cambridge University Press, 1999) on the number of tilings of quasi-hexagonal regions on the square lattice with every third diagonal drawn in. We also obtain a generalization of Douglas' Theorem on the number of tilings of a family of regions of the square lattice with every second diagonal drawn in.